A dispenser has been conventionally used for the purpose of extruding a paste-type material such as a lubricating grease or edible material such as mayonnaise bit by bit at a constant rate. The known dispenser includes a comparatively rigid cylindrical body which is provided at its one end with an extrusion opening and opened at its other end, a floating piston insertable into the cylindrical body through the open end of the latter to fit rather tightly but movably in the cylindrical body, and an extruder having a receiving portion of a semi-circular cross-section for receiving the cylindrical body. The cylindrical body is charged with a paste-type material and is received in the receiving portion of the extruder. The extruder has an operating portion for plunging the piston into the cylindrical body received in the receiving portion. The piston is advanced a predetermined distance at each operation of the operating portion., so that a predetermined amount of the paste-type material is extruded in response to each plunging operation of the piston.
The described known dispenser inconveniently requires refilling of the cylindrical body each time the dispenser is used. In addition, the paste-type material tends to be contaminated during the filling of the cylindrical body, and this causes a serious problem particularly when the material is an edible one such as mayonnaise.